The present invention relates to a metal cutter tool of the type used for producing profiled workpieces by chip cutting methods. More particularly, the invention relates to shaper cutters incorporating inserted members.
Shaper cutters for machining gears or similar profiled workpieces have taken a variety of forms over the years, but typically have included a conical or cylindrical tool body having a series of circumferentially spaced teeth. In order to permit cutting by the leading edges of the cutter teeth, the periperal surfaces of the teeth are tapered away from these leading edges to provide a clearance region for the metal shavings or cuttings. It has been found that coating the teeth with titanium nitride or like wear resistant coatings enhances their cutting performance and edge wear.
There are a number of practical objections to this prior art tool design, relating to the need for intermittently regrinding the teeth to maintain desired sharpness. Such regrinding impairs the precision of the tools cutting profile, requires adjustments in the mounting of the cutter relative to the workpiece, and removes the surface coating. Therefore, investigators have tried a number of alternative approaches to designing an economical, long-lived cutter.
One approach to the economical design of shaper cutters as well as hobs is the "inserted blade" type, wherein the tool includes a support structure with a plurality of inserted teeth. Illustrative patents include U.S. Pat. Nos. 2,498,721; 2,706,848; 3,520,044; 3,571,875; 3,688,368; 3,740,808; 4,102,583; 4,135,414; 4,170,161; 4,188,161; and 4,197,039. Another approach has been to provide a plurality of stacked rings with cutting edges defining a composite cutting profile. This technique is shown in U.S. Pat. Nos. 3,303,554; 3,762,006; and 4,218,159.
European patent publication No. 132,350, filed July 12, 1984, discloses a gear shaper cutter including a flexible wafer clamped between a tool body and a clamping ring. Unlike the tool of the present invention, this shaper cutter utilizes a concave mounting surface of the tool body against which the wafer is flexed to provide a positive rake angle. In order to achieve the needed clearance angles for the cutter wafer teeth, the wafer is ground with tapered "back angles". This wafer profile prevents inversion and reuse of the cutter wafer.
Accordingly, it is a primary object of the invention to provide improved designs for shaper cutter tools. Such design should enjoy excellent cutting characteristics, while providing improved economies of use.